Intel on Friday said it is researching technology to harvest free energy from the environment, which could lead to devices such as mobile phones running for indefinite periods without recharging.

The company is working on tiny sensors that can capture energy from sources such as sunlight and body heat. In the future, such energy could be used to power personal electronic devices such as cell phones.

There are already watches available that are powered by body heat, as well as prototype smartphones with display screens that double as solar cells, said Justin Rattner, chief technology officer at Intel, during a press event. Intel is also looking at powering a mobile phone by harvesting the energy the user generates by moving the phone's trackball. The radiation of cell phone or TV signals might also be used to power devices.

"Wouldn't it be nice if, in fact, you were able to go almost indefinitely without charging the battery, if you were able to scavenge enough free energy from the environment?" Rattner said.

Intel's initial efforts revolve around the sensors, which could power themselves using free energy. Recharging themselves by scavenging free energy allows the sensors to continuously record and transmit readings over wireless networks, without any human involvement.

For example, an accelerometer buried in the wall of a building could automatically recharge itself by harvesting the energy of radiation from a cell phone tower, allowing it to continuously take and transmit readings of the building's movement.

"It wouldn't have any batteries, you wouldn't have to come out and service them, and you don't have to run any power. They are completely self-contained, and most importantly, self-powered as a result of scavenging energy from the environment," Rattner said.

Intel has also designed a self-charging neural implant that can monitor bodily functions and transmit its readings wirelessly, Rattner said.

"I never have to ... come along with some sort of external fixture and have to recharge this. These become ... install-and-forget systems, because they can scavenge energy from the environment and power themselves up," Rattner said.

Intel has not marketed such a sensor yet, as its research is still ongoing, Rattner said. Sensors use just a fraction of the power demanded by typical mobile devices, and it may take a while before the energy-harvesting technology can power larger items.

For now, the research is intended to provide a broader view of energy harvesting, and many Intel product groups are showing interest in it.

"We haven't been driving it as an Intel product; it's not on anyone's road map at this point. It's part of our broader effort in both sensors and energy harvesting," Rattner said.